This application is not based upon any pending domestic or international patent applications.
This application is not referenced in any microfiche appendix.
The invention described herein is a method of dispensing inhibitor in a gas pipeline in which a pig is moved through the interior of a pipeline by the flow of pressurized gas and distributes treating liquids, such as inhibitors, subsisting in the lower portions of the pipeline.
The invention described herein is a pipeline pig that provides a method of applying a treating fluid, such as an inhibitor, within a pipeline to specific longitudinal areas along the inner wall of the pipeline and particularly to the upper interior portions of the interior wall of a pipeline.
Pipelines, particularly those designed to carry large volumes of gas under pressure, are customarily made of metal and usually of steel. Steel is the preferred metal for construction of a pipeline due to its inherent strength, availability and economy. However, steel is subject to corrosion as a consequence of oxidation or reaction with gasses or liquids, such as water, that is commonly encountered when large volumes of gas are delivered through a pipeline. To combat corrosion a standard technique employed by many operators of pipelines is to periodically deposit inhibitor liquid within the pipeline. The liquid can be moved by the flow of gas through the pipeline or more commonly, by the use of pipeline pigs inserted into the pipeline that are moved by the flow of gas, the pigs serving to provide a moving plunger within the pipeline that tends to sweep liquid within the pipeline before it and to therefore move the liquid through the full length of the pipeline.
One method of applying a treating liquid to the interior of a pipeline is called xe2x80x9cbatchingxe2x80x9d in which treating liquid is captured between two pipeline pigs that move in tandem through a pipeline pig with the treating liquid therebetween. Although this method is widely accepted and used it does not insure that the upper quadrant of the interior of a pipeline is adequately coated with or exposed to the treating liquid.
A second method of treating the interior cylindrical surface of a pipeline is called the xe2x80x9cinjection method.xe2x80x9d In this method, the treating liquid is injected directly into the pipeline and is moved by gas flow to carry the liquid through the length of the pipeline. This method is costly and usually requires that treating liquids be more or less continuously injected into the pipeline. There is no direct application, in this method, of the treating liquid to the inner wall since liquid simply rests on the bottom interior surface of the pipeline as it moves along the length of the pipeline.
To combat these problems, the pipeline pig of this invention provides a method of distributing liquid present in the lower portion of a pipeline to the interior upper quadrant of the pipeline interior as the pig passes by the flow of gas through the length of the pipeline.
For background information relating to pipeline pigs that have similar uses and applications reference may be had to the following previously issued United States patents and a U.S. patent application publication:
The invention herein is a pipeline pig that is moved through the interior of a pipeline by the flow of pressurized gas and that provides for improved distribution of treating liquid, such as an inhibitor, subsisting in the lower portion of the pipeline. The pipeline pig has a longitudinal pig body having a forward end and a rearward end. Forward and rearward centralizers are affixed to the pig body by which it is supported centrally in the pipeline and by which it is moved by gas flow through the pipeline. These centralizers are preferably in the form of elastameric cups or disks, each having an external circumferential surface that closely conforms to the internal circumferential surface of the pipeline.
A bypass passageway is provided through the pig body that communicates with the pipeline interior rearward end. A separate siphon passageway, communicates with a lower portion of the pipeline interior, the siphon passageway being preferably positioned adjacent the front end of the pig body.
A venturi is supported by the pig body in communication with the siphon passage and with the bypass passageway. A flow of gas through the bypass passageway serves to draw liquid through the siphon passageway and, employing the Bernoulli effect, the liquid from the siphon passageway is discharged onto an upper portion or upper portions of the interior pipeline wall. In this way, as the pipeline pig is moved through the interior of a pipeline, liquid is moved by the application of Bernoulli""s law to be sprayed onto the upper interior portion of the pipeline.
The method of distributing liquid present in the lower portion of a gas pipeline to the interior upper surface of the pipeline includes the steps of passing a pig having a venturi therein that is activated by gas pressure taken from a rearward end portion of the pig siphoning liquid from the lower interior portion of the pipeline by venturi action, and distributing the siphon liquid to the pipeline upper interior surface.
A better and more complete understanding of the invention will be obtained from the following description of the preferred embodiments, and the claims, taken in conjunction with the attached drawings.